I'm wondering if one of the (now many) external battery packs available for recharging smart phones and tablets would also be suitable for extending the operating time of an R16/24, if used away from mains power...in preference to using 6 x AA's internally ?

Most of them recharge from the USB port of a computer, and would only require the correct diameter barrel DC connector to be fitted in place of the phone connector.

Would there be any risk of it frying the internals of the Rxx, given that it's a high output recharger ? The R16 requires 1A from an external mains transformer, and that's typically what these packs supply too...presumably they're all typically 5 volts DC ?

6 AA batteries put out 9 volts dc and usb phone chargers supply 5 volts dc. A better option might be to use external battery holders that can hold six C or D batteries. They have the same voltage level and can retain more current than AA batteries.

Jim_Fogle wrote:6 AA batteries put out 9 volts dc and usb phone chargers supply 5 volts dc. A better option might be to use external battery holders that can hold six C or D batteries. They have the same voltage level and can retain more current than AA batteries.

The way I'm considering using the external battery, it would connect into the same DC In socket that the AD14 power adapter plugs into.....and the specs on the AD14 unit says it supplies 5 volts DC at 1A, so I'm hoping the external battery would match those output specs as well. Hence, no need for 9 volts, as it wouldn't be connected to the AA battery bay.

AlexeiY wrote:
When I use USB power from my computer, the R24 can only be used as a card reader or a DAW controller, not a standalone recorder. Am I missing something?

hoodoo voodoo wrote:
Yes that's what mine does also....and as for the other USB connector alongside it (labelled "Host") I'm pretty sure that's only for connecting a USB thumb drive to for data transfer ?

Perhaps the R16 can be USB powered while using the record function. Hopefully hoodoo voodoo will let us know.

The USB 2.0 design standard limits the current drain for each receptacle to a maximum of 0.5 amps. This test could pop the power runs right off the circuit board. On the other hand Zoom hardware engineers may have dead headed the USB power connections to prevent accidental damage to the circuit board.

Zoom USA are of some help..but they clearly haven't made any first hand experiments along these lines (as it's a non-standard, non-approved kludge on my part). Their response to the same query I posted here is:
"There is a chance that you may fry your unit if it puts out too much power. But we would suggest the AD14 power adapter for the best result. But please let us know if this works"
--Zachary Wiegand, Customer Support

hoodoo voodoo wrote:Zoom USA are of some help..but they clearly haven't made any first hand experiments along these lines (as it's a non-standard, non-approved kludge on my part). Their response to the same query I posted here is:
"There is a chance that you may fry your unit if it puts out too much power. But we would suggest the AD14 power adapter for the best result. But please let us know if this works"
--Zachary Wiegand, Customer Support

So I'm on my own on this one.....

The only thing I'd really be concerned with is the voltage level. Batteries don't "push" their capacity into a load -- the load device "draws" (or "sucks") what it is capable of passing/using.

Granted, in the case of an internal short, a battery can dump a LOT of current*, whereas a limited current wall-wart may fry instead. But in this case you already have a problem in the device.

* Consider radio controlled race cars. The classical battery pack was around 7.2-8.4 volts, rated 1400mAh -- or 1.4A distributed over one hour of usage; race cars typically were geared to drain that pack in 4-5 minutes (the length of one race). That means the cars were drawing 17A of current -- over 120W!

"There is a chance that you may fry your unit if it puts out too much power. But we would suggest the AD14 power adapter for the best result. But please let us know if this works"
--Zachary Wiegand, Customer Support

All you need is to add a current limiter if the source is 5 VDC, other wise you'll also need a 5 V regulator circuit as well. the 7800 series regulators can provide a regulated VDC output, in your case you'll need a the 7805 regulator or use an NPN BJT to regulate the voltage source using a 4.3 V zener. There are many circuits examples available on the web for regulating the output voltage and limit the output current as well. Although some circuits are more efficient that others. In the 7805 circuit, it will not be as efficient as the BJT or FET regulating circuit.

BobF, I agree but my portable source is a motorcycle battery and it needs current limiting in the event someone decides to spill beer on the board. Without current limiting, all is fine, but this has happened to my pedal board, so now I use current limiting.